Bulk materials, finished products, parts and components, and also waste materials are frequently transported in large containers that resemble the body portions of semi trailers apart from the undercarriage and wheels. When configured with fittings for engagement with standardized lifting and manipulation fittings, the same containers are useful for transport by ship, rail or roadway, i.e., as intermodal containers.
There are a number of standard sizes for intermodal containers. A typical container short size container is approximately twenty feet long, six to eight feet wide and four to twelve feet deep. Another standard size is forty feet in length. Fittings for cranes and other handling devices are provided, for example, at all eight corners. The fittings can be engaged by manipulators or received by fixed berthing fittings on a ship deck or hold, or on a rail or truck transport bed. The same sort of fittings can attach between the corners of adjacent or stacked containers to secure the containers as well as to align the containers in a registered stack or array.
The corner fittings typically have plates or cast hollow boxes, with oblong entry holes. The devices that engage in the corners, namely the twistlocks, have non-round insertion parts with cross sections that are complementary to the entry holes. When inserted, the insertion parts are rotated on their shafts, e.g., by 90 degrees, using any of various manual or powered mechanical drive means. The rotation renders the cross sections no longer complementary, thereby preventing axial withdrawal without first re-aligning the non-round insertion part with the entry hole. Various types of twistlocks are known. One supplier is Tandemloc, Inc., 824 Highway 101, Havelock, N.C. 28532, tel. (252)447–7155.
Intermodal containers most typically are closed by permanently attached walls except at end doors. One or more doors might be hung on vertical hinge axes for access or on a horizontal hinge axis for dumping. It is known, however to outfit a container with openings such as an open top. A variety of open top containers are available, for example from Wastequip, Inc., 25800 Science Park Drive, Cleveland, Ohio 44122, tel. (216) 292–2554.
A container with a top opening can be fitted with a lid or cover to prevent the escape of loose material from the container and to prevent ingress of water. Among other possibilities, tarpaulin covers, sliding lids and hinged top doors can be used as covers. Advantageously, a lid arrangement can cover just a portion of the top opening of the container. The lid might also cover a top opening that is bounded at a perimeter defined by the outer walls of the container.
Certain roll-top arrangements are available from Wastequip (see for example, U.S. Pat. No. 6,364,153—Petzitillo). The lid is arranged to roll to one side wall and then to pivot to move clear of the opening. These arrangements require two distinct structures. One structure is the rolling and pivoting support mechanism that handles moving the lid over the open top of the container or clear of the open top. A second structure is provided for affixing the lid onto the container when in place. The lid is not related to any intermodal fittings or to any devices such as twistlocks that resemble intermodal fittings.
A roll top is convenient in relatively small containers. For larger containers, the lid may be too large to be manipulated by one or two people. It is possible to provide a lid that is placed or lifted in a vertical direction from an opening atop the container. Such a lid can be handled by a crane equipped with an engagement device. A frame, known as a spreader, can be suspended from a crane and has members placed to attach to the lid at spaced points such as at the four corners of a rectangular lid. this allows the position of the lid to be controlled by the position of the spreader frame.
A lid-lift spreader generally conforms to an outer rectangular dimensions of the lid and is much the same as the sort of spreader that is used to engage with the intermodal fittings at the corners of containers, when lifting a whole container as opposed to the lid alone. The engagement devices therefore can comprise four twistlocks. The engagement devices and the lid engagement devices (like intermodal corner structures) have mating non-round male and female elements. These elements are aligned, axially inserted, and relatively rotated. This locks the elements so that the spreader is engaged to the lid (or to the intermodal container) and the crane can lift and manipulate the lid (or the container) as needed. Engaging and lifting the lid is a different problem from attaching the lid to the container.
Current lids are designed to engage a raised lip disposed about the rim of the opening at the top of the container. The lid is designed to fit over and around the lip and is thus generally prevented from being laterally dislodged from the opening. A separate lid locking mechanism may be provided to prevent tampering with the container contents or to further assure that the lid will stay in place on the container.
It would be desirable to combine the beneficial features of a mechanism for engaging and manipulating a lid for an intermodal container with a locking mechanism that will assure retention of the lid on top of the container.